Senior U.S. officials converged on South Asia yesterday, hoping to persuade India and Pakistan to lower the tensions between them after the Mumbai attacks, and to avoid an escalation that could jeopardize U.S. war efforts in neighboring Afghanistan.

Their most urgent message is directed toward India, where Secretary of State Condoleezza Rice and Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, planned to appeal to the government to accept Pakistan's offer to jointly investigate the assault with U.S. assistance, a senior Bush administration official said.

"The goal is to say, first, this is really serious," the official said. "It is qualitatively different for us," because six Americans were among nearly 200 killed by terrorist gunmen believed to have traveled to the Indian seaside metropolis by boat from Pakistan. "But more important, we want to work with you and the Pakistanis. The only way we're really going to deal with the terrorist threat is to get the Pakistanis to cooperate in the investigation."

In Pakistan, the administration hopes to persuade the newly elected democratic government to move forcefully against domestic terrorist groups that initially were formed with the assistance of Pakistani intelligence to attack India along the two countries' disputed border in Kashmir. India has charged -- and U.S. intelligence believes -- that the Mumbai attacks were carried out by one of those groups, Laskhar-i-Taiba, or Army of the Pious.

Adding his voice to the calls for calm, Defense Secretary Robert M. Gates spoke yesterday of the importance of "restraint" on the part of both nations.

"But it's also important to find out who was responsible," Gates said at a news briefing. "I think what we would like to see is both countries work together to make sure that something like this doesn't happen again." Gates added that he was unaware of any request by India for U.S. training or equipment to help with its counterterrorism efforts, or any U.S. offer to provide such aid.

President-elect Barack Obama announced Monday that he would retain Gates as defense secretary. Asked twice about an Indian response to the attacks, Obama first demurred, citing "delicate diplomacy" and the reality of "only one president at a time" in the United States. Pressed on whether India has the same right as the United States to respond to terrorist threats, he said he thinks that "sovereign nations obviously have a right to protect themselves."

Although U.S. relations with India rarely came up during the presidential campaign, Obama told Outlook India magazine in an interview in July that "we are both victims of terrorist attacks on our soil." Among many shared interests, he said, is "our common strategic interests" that call for "strengthening U.S.-India military cooperation."

On counterterrorism, India's skepticism of Pakistan and the United States draws on recent history. The last threatened India-Pakistan war, following a Lashkar attack on the Indian Parliament in December 2001, was averted by strong U.S. intervention with both governments. As the two countries massed hundreds of thousands of troops at the disputed border, the administration pushed then-Pakistani President Pervez Musharraf to publicly pledge to combat militants inside Pakistan, and persuaded India to accept the promise.

Although a number of militants were arrested, most were quickly released. "What the administration is trying to do now is to influence the Pakistanis to finally bring these guys under control, while working to convince the Indians that the commitment to working with the Pakistanis is credible," said Ashley Tellis, a South Asia expert at the Carnegie Endowment in Washington.

The United States has "made a series of such commitments to India going back to 2001, and simply could not or would not deliver," Tellis said. "The Indians are now asking why it is they should believe the administration when it says it's going to redouble those efforts."

U.S. leverage with India is largely limited to goodwill and the promise of continued economic and diplomatic ties. "There is a lot of good faith from the Indians on the nuclear deal," last year's U.S.-Indian agreement on nuclear energy cooperation, the administration official said. "We've been with them on a whole lot of things recently, and I think we can be with them on terrorism, too."

Rice and Mullen hope to convince their Indian counterparts that the difference this time is that Musharraf, an army general who seized power in Pakistan in a 1999 coup, has been replaced by a democratic government committed to moving against all extremist groups within its borders.

In recent months, the new Pakistani government had reached out to India, offering to begin discussions about resolving the Kashmir issue and cracking down on militant camps along the disputed northeastern frontier.

To the gratification of the Bush administration, Pakistan's military had turned its attention away from India toward the western border with Afghanistan, where al-Qaeda and the Taliban are ensconced. U.S. officials have praised a Pakistani offensive in the mountainous west, and they have concluded a secret agreement with the Pakistani government allowing them to fire missiles from unmanned Predator aircraft based in Afghanistan at Taliban fighters inside Pakistan's territory.

Gates said yesterday that he had seen no indication that Pakistan's military was diverting its forces from the west toward the east. But U.S. officials fear that is inevitable if tensions are not quickly resolved.